// Parses all wavefunctions.
internal static (StateType, double, object) ToWavefunction(V0_2.State state)
{
StateType method = ParseInitialStateMethod(state.Method);
double energy = state.Energy != null ? state.Energy.Value : 0.0;
List <List <string> > superposition = state.Superposition ?? new List <List <string> >();
ClusterOperator clusterOperator = state.ClusterOperator;
object outputState;
if (method == StateType.SparseMultiConfigurational)
{
outputState = ToSparseMultiCFWavefunction(superposition);
}
else if (method == StateType.UnitaryCoupledCluster)
{
outputState = ToUnitaryCCWavefunction(clusterOperator);
}
else
{
throw new System.ArgumentException($"initial state `{state.Label}` is not recognized or implemented.");
}
return(method, energy, outputState);
}
// Parses UCC wavefunction.
internal static UnitaryCCWavefunction <SpinOrbital> ToUnitaryCCWavefunction(ClusterOperator clusterOperator)
{
var outputState = new UnitaryCCWavefunction <SpinOrbital>();
var oneBodyTerms = clusterOperator.OneBodyAmplitudes ??
new List <List <string> >();
var twoBodyTerms = clusterOperator.TwoBodyAmplitudes ??
new List <List <string> >();
foreach (var element in oneBodyTerms.Concat(twoBodyTerms))
{
// First item is the amplitude.
double amplitude = double.Parse(element.First().ToString(), System.Globalization.CultureInfo.InvariantCulture);
// Second to last are fermion operators.
IEnumerable <LadderOperator <SpinOrbital> > operators = element
.Skip(1)
.Select(o => V0_1.ParsePolishNotation(o.ToString()));
var ladderSequence = new LadderSequence <SpinOrbital>(operators);
// Terms are assumed to be in normal order.
var sortedOperator = new IndexOrderedSequence <SpinOrbital>(operators);
outputState.Set(sortedOperator, new Complex(amplitude, 0.0));
}
var reference = new List <List <string> >()
{
clusterOperator.Reference
};
outputState.Reference = new SingleCFWavefunction <SpinOrbital>(
ToSparseMultiCFWavefunction(reference).Excitations.Single().Key.ToIndices()
);
return(outputState);
}